#include <iostream>
using namespace std;

int main()
{
	double s;
	cin >> s;
	double result = 2;
	double sum = result;
	int count = 1;
	if(int(s) == 1 || s>0.01 && s < 1.01)
	{
		cout << 1 << endl;
		return 0;
	}else if(s == 0.00){
		cout << 0 << endl;
		return 0;
	}
	while(sum < s){
		result = result * 0.98;
		count = count + 1;
		sum = sum + result;
	}
	cout << count << endl;
	
	return 0;
} 
